Gene Duplication and Nucleotide Substitution in Evolution

Nei, Masatoshi

doi:10.1038/221040a0

Cited by 151 publications

(68 citation statements)

References 18 publications

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“…(iv) One genomic cluster often contains OR genes belonging to different phylogenetic clades that are distantly related. Observation i suggests that the OR gene family is subject to the birth-and-death model of evolution, in which new genes are formed by gene duplication and some of the duplicate genes differentiate in function, whereas others are inactivated or deleted from the genome (27,28). In fact, our joint phylogenetic analysis of human and mouse OR genes, which will be published elsewhere, has confirmed this assertion (see also Fig.…”

Section: Discussionsupporting

confidence: 71%

Evolution of olfactory receptor genes in the human genome

Niimura

Nei

2003

Proc. Natl. Acad. Sci. U.S.A.

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Olfactory receptor (OR) genes form the largest known multigene family in the human genome. To obtain some insight into their evolutionary history, we have identified the complete set of OR genes and their chromosomal locations from the latest human genome sequences. We detected 388 potentially functional genes that have intact ORFs and 414 apparent pseudogenes. The number and the fraction (48%) of functional genes are considerably larger than the ones previously reported. The human OR genes can clearly be divided into class I and class II genes, as was previously noted. Our phylogenetic analysis has shown that the class II OR genes can further be classified into 19 phylogenetic clades supported by high bootstrap values. We have also found that there are many tandem arrays of OR genes that are phylogenetically closely related. These genes appear to have been generated by tandem gene duplication. However, the relationships between genomic clusters and phylogenetic clades are very complicated. There are a substantial number of cases in which the genes in the same phylogenetic clade are located on different chromosomal regions. In addition, OR genes belonging to distantly related phylogenetic clades are sometimes located very closely in a chromosomal region and form a tight genomic cluster. These observations can be explained by the assumption that several chromosomal rearrangements have occurred at the regions of OR gene clusters and the OR genes contained in different genomic clusters are shuffled.

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Section: Discussionsupporting

confidence: 71%

Evolution of olfactory receptor genes in the human genome

Niimura

Nei

2003

Proc. Natl. Acad. Sci. U.S.A.

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245

223

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“…As a result, existent salmonids can be considered pseudo-tetraploid, The Journal of Experimental Biology 216 (7) with duplicate copies of most genes (Davidson et al, 2010). Such gene duplication may allow for diversification of enzyme function without compromising existing capabilities (Nei, 1969;Lynch, 2007). Duplication of NKA alpha subunit genes may have relaxed the selective pressure on some paralogs such that they could acquire novel functions and accumulate distinct regulatory elements.…”

Section: Discussionmentioning

confidence: 99%

Differential regulation of sodium–potassium pump isoforms during smolt development and seawater exposure of Atlantic salmon

McCormick

Regish²,

Christensen

et al. 2013

Journal of Experimental Biology

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SUMMARYFreshwater and seawater isoforms of the alpha subunit of Na + /K + -ATPase (NKA) have previously been identified in gill ionocytes of Atlantic salmon (Salmo salar). In the present study we examine the abundance and cellular localization of these isoforms during the parr-smolt transformation, a developmental process that is preparatory for seawater entry. The abundance of NKAα1a was lower in smolts than in parr, remained relatively constant during spring and decreased in summer. NKAα1b increased tenfold in smolts during spring, peaking in late April, coincident with downstream migration and increased salinity tolerance. NKAα1b increased a further twofold after seawater exposure of smolts, whereas NKAα1a decreased by 98%. The abundance of NKAα1b-positive, and NKAα1b and NKAα1a co-labeled ionocytes increased during smolt development, whereas the number of NKAα1a cells decreased. After seawater exposure of smolts, NKAα1b-positive ionocytes increased, NKAα1a-positive cells decreased, and co-labeled cells disappeared. Plasma growth hormone and cortisol increased during spring in smolts, but not in parr, peaking just prior to the highest levels of NKAα1b. The results indicate that the increase in the abundance of NKAα1b during smolt development is directly linked to the increase in salinity tolerance that occurs at this stage, but that significant changes also occur after seawater exposure. Spring increases in circulating levels of growth hormone and cortisol indicate that these hormones may be instrumental in upregulating NKAα1b during smolt development.

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“…It had long been assumed that one copy of the duplicated genes might almost always become a pseudogene, unrecognizable 'junk' DNA or nonfunctional ('silenced') relatively quickly, in the order of only a few million years at best, because of the potentially rapid accumulation of deleterious mutations [24]. Among other forces, several population-wide genetic factors might determine how quickly duplicated genes decay into non-functional genes [2,10,25,26,27 • ].…”

Section: To Lose or Not To Lose?mentioning

confidence: 99%